Conventional valves are known for controlling and or regulating a fluid flow circulating through a pipe, such as flap valves, ball or spherical valves, gate valves, etc. All of them are very known in the art and, although they have worked satisfactorily in general terms, all of them have failed in obtaining a smooth regulation of the fluid flow, particularly when opening and closing the valve.
A gate valve comprises a body defining a fluid passage connected at both sides of the valve body to a pipe. A gate slides up and down within the valve body and across such a passage so as to fully open or to close the passage in respective end positions of the gate. Between the end positions, the gate partially closes the passage whereby the fluid flow is regulated. However, close to the end positions, and particularly when the valve is rapidly or quickly closed, the gate suddenly interrupt the fluid flow and, therefore, a violent pressure change is generated in the fluid, within the pipeline. This is known as hydraulic ram and has undesirable effects, sometimes with dangerous results, in the pipe, valve, fittings, couplings, etc.
The ball or spherical valve comprises a valve body housing a ball, the ball being the element that regulates the fluid flow passing through a passage defined within the body. In like manner, this valve has the same drawbacks explained above. In summary, all these valves generates a violent change of pressure within the fluid when passing from a regulation mode to a close mode and vice versa.
Other attempts to overcome the above explained problem involved the installation of several and different valve and regulating devices for obtaining a stepped control on a fluid flow.
In addition, the hydraulic ram is very dangerous in the case of fluids others than water, for instance natural gas, gasolines, chemicals, etc.